1. Field of the Invention
The present invention is directed to the field of power semiconductor modules and, more particularly, to a power semiconductor module having a pressure contact embodiment, for disposition on a cooling component, and a method for producing such a semiconductor module.
2. Description of the Related Art
In the prior art, such as German Patent Application No. DE 197 19 703 A1, known power semiconductor modules comprise a housing with at least one electrically insulating substrate disposed thereon, preferably for direct mounting on a cooling component. The substrate in turn includes an insulation body having a plurality of metal connection tracks located thereon. The connection tracks are insulated from one another. Power semiconductor components are located on, and connected to, these connection tracks. Moreover, known power semiconductor modules have terminals for external load and auxiliary terminals and also have internally located connecting elements. These connecting elements are usually wire bond connections.
Pressure-contact power semiconductor modules are also known, of the kind disclosed in German Patent Applications Nos. DE 42 37 632 A1 and DE 199 03 875 A1, or in German Patent No. DE 101 27 947 C1. In the first of these references, the pressure device has a stable, preferably metal, pressure element for pressure buildup, an elastic pad element for pressure storage, and a bridge element for introducing pressure to separate regions of the substrate surface. The bridge element is preferably formed as a molded plastic body with a face oriented toward the pad element, from which face many pressure prongs radiate in the direction of the substrate surface.
By means of this kind of pressure device, the substrate is pressed against a cooling component, and the heat transfer between the substrate and the cooling component is thus permanently assured. The elastic pad element generally maintains constant pressure conditions under various thermal loads and over the entire service life of the power semiconductor module.
German Application No. DE 199 03 875 A1 develops this known pressure element further so that, on the one hand it has an especially advantageous ratio of weight to stability, and, on the other hand, it has electrically insulated lead throughs. To that end, the pressure element is formed as a molded plastic body over a metal core. This metal core has recesses for the leadthrough of terminals, preferably auxiliary terminals in a spring contact embodiment. The molded plastic body surrounds these recesses in such a way that the auxiliary terminals are electrically insulated from the metal core by the plastic molded body.
Further-developed pressure elements are also known which have many pressure prongs on their surface oriented toward the substrate. Preferably, the metal core also has a pre-set sag. When the two provisions are combined, a pressure element of this kind can furnish the entire functionality of an aforementioned pressure device.
German Patent No. DE 101 57 947 C1, describes a power semiconductor module in which the load terminals are embodied such that they extend in portions closely adjacent to and perpendicular to the substrate surface and have contact feet extending therefrom that furnish the electrical contact with the conductor tracks while at the same time exerting pressure on the substrate and thereby establish its thermal contact with a cooling component. The pressure is introduced and stored using means of the prior art.
German Patent Application No. DE 10 2004 021 927 A1, discloses a method for internally insulating power semiconductor modules. In contrast to the known prior art, they are not filled with an insulating silicone gel up to a defined fill level, rather, this application teaches a method for coating the components and connecting elements to be insulated which is quite economical in terms of the amount of silicone gel needed to the insulation form.